New medicines could prolong lives of AIDS patients, studies indicate Drugs also gain power in new combinations

February 02, 1996|By KNIGHT-RIDDER NEWS SERVICE

WASHINGTON -- In the fight against AIDS, this week was a rarity: a moment of encouragement.

Researchers attending the Third Conference on Retroviruses and Opportunistic Infections here heard reports from two drug companies that a new type of drug can significantly prolong the lives of AIDS victims.

"We're on the threshold of being able to add years of quality life to AIDS patients," Jack Killen, director of the National Institute of Health's AIDS research division, said this week.

The new drugs, called protease inhibitors, are much more effective than the older class of AIDS drugs, called reverse transcriptase inhibitors.

Each strikes at a different point in the cycle of the virus' spread. And when the new drugs are combined with the old ones, they seem to be more powerful.

"This is not the end of AIDS," Ashley Haase, a University of Minnesota microbiologist, said of the new drugs, "but maybe its conversion into a chronic infection which we could have an impact on."

Dr. Haase is one of the country's senior advisers on AIDS policy.

Scientists are cautious about overstating the power of the new medications: The drugs have not been tested on a large number of people for a long time, and "powerful" weapons against the disease have proven to be letdowns in the past.

Moreover, they're very expensive.

People with AIDS have learned that hope can be a terrible thing. The urge to clutch at straws comes so easily.

"We go in cycles of hope and depression," agreed Ryland Roane, an AIDS educator with Virginia's department of health, who is infected with the AIDS virus. "We're in one of those cycles where we're getting excited right now."

One of the new drugs is called ritonavir, produced by Abbott Laboratories, and the other is indinavir, produced by Merck & Co.

When researchers added ritonavir to the medications of a test group drawn from more than 1,000 AIDS patients and compared them with those who got only conventional treatment, deaths were reduced by half in six months, said Andre Pernet, Abbott's head of research and development.

The combination treatment also cut opportunistic infections -- the diseases that ravage AIDS patients' weakened immune systems and usually cause death -- by two-thirds.

Merck's indinavir, researchers found, wiped out almost all measurable traces of the virus, when it was combined with older drugs, AZT and 3TC. The Merck tests studied fewer than 30 AIDS patients and lasted four to six months.

like cornering the virus from different angles," said Dr. Pernet, on why combination therapies seemed to be more effective.

"We have demonstrated a six-month remission," he said, when asked how long the therapy could suppress the virus. "How long is that going to last? Every month we gain a month."

Neither of the new protease inhibitors is yet available on the U.S. market. Abbott has applied to the Food and Drug Administration for approval, and Merck plans to do the same.

The only protease inhibitor currently available is Hoffman-La Roche's Saquinavir, which isn't as powerful as the new drugs, scientists said.

The human immunodeficiency virus (HIV), which causes AIDS, is known for its ability to eventually elude any drug thrown at it. It is transmitted through infected body fluids, usually through unprotected sex or shared intravenous needles.

Once inside the body, it infiltrates cells and commandeers the cells' genetic tools. It then uses the tools to make copies of itself.

From the time of infection onward, the body's immune system wages a long battle against the virus. But the virus keeps mutating until it finds chinks in the immune system's armor, which translates into the patient's getting "full-blown AIDS." The process often takes a decade.

Patients' immune systems rapidly collapse after that. They become defenseless against new predators -- the infections that are the harbingers of death.

The new drugs are likely to raise ethical dilemmas: They will probably be beyond the financial reach of many AIDS patients, certainly most patients outside the United States, where the disease is wreaking the greatest havoc and where most new cases will occur well into the next century.